The invention relates to a hydraulic lifting device on harvesting machines to lift and lower a harvesting implement. A lifting apparatus is already known wherein a reference pressure corresponding to the ground bearing load of a mower table is applied against lifting cylinders via a relief valve, wherein the reference pressure is not undercut. It is thereby possible in certain constructions, that by lowered setting of the reference pressure by the actuating valves results in a momentary lifting of the mower table, thereby increasing the risk of accident.